I believe it is the American obsession with whitening and straightening that causes that perception.
Not really. Plenty of nationalities have straight teeth. (Americans not so much, because a lot are of English decent.)
I hope people aren't getting offended by this talk. My ancestry gave me a big-ish nose.

(Not Adrian Brody big, but still.)

There's not much I can do about it, and I can't really be offended when people say, "race X" or "nationality Y has big noses".